1. Field of the Invention
The invention relates to a method of reducing noise of a video signal, and more particularly, to a method of reducing noise of a video signal, which is capable of detecting and reducing noise generated in a quantization step of an encoding process.
2. Description of the Related Art
Noise reduction in a conventional video transcoding process is performed by detecting noise using the intra-picture coding mode or the motion vector of a block and filtering the noise.
However, the conventional noise reduction method cannot detect noise resulting from variations in Quantization Parameters (QPs) that may be encountered during an encoding process.
FIG. 1 is a schematic view for explaining noise that may be generated in a conventional video transcoding system.
Referring to FIG. 1, the conventional video transcoding system includes a camera 10 and a transcoder 20. The camera 10 includes an image pickup unit 11, which picks up an image, and a first codec encoding unit 12, which converts a bitstream to an arbitrary first codec to transmit the picked-up image.
The transcoder 20 receives the converted bitstream, decodes the received bitstream using a first codec decoding unit 21, and converts the decoded bitstream to a second codec using a second codec encoding unit 22.
However, a transcoding process performed by the conventional video transcoding system may include pickup noise 30, which is generated during the pickup of an image by the image pickup unit 11, first quantization noise 40, which is generated during the encoding of the image by the first codec encoding unit 12, and second quantization noise 50, which is generated during the encoding of the image by the second codec encoding unit 22.
Accordingly, the necessity of a method to reduce quantization noise generated during the conversion of a bitstream from an arbitrary first codec to an arbitrary second codec has arisen.